As a related vehicle seat, Patent Literature 1 discloses a seat including: side panels arranged on the left and right sides of a seating part of the seat; a front member laid between and fixed to front end portions of the side panels; and a rear member laid between rear end portions of the side panels and fixed to only one of the side panels. Without increasing in weight, this vehicle seat is configured to prevent vibrations of the vehicle body caused by travel from being transmitted to the seat and thereby avoid sympathetic vibrations of the seat (this phenomenon will be referred to as resonance. The same applies hereinafter).